Systems and methods for reducing effluent build-up in a pumping exhaust system

ABSTRACT

A method for reducing effluent buildup in a pumping exhaust system of a substrate processing system includes, during a substrate treatment process, arranging a substrate on a substrate support in a processing chamber; supplying one or more process gases to the processing chamber; supplying an inert dilution gas at a first flow rate to the pumping exhaust system; performing substrate treatment on the substrate in the processing chamber; evacuating reactants from the processing chamber using a pumping exhaust system. The method includes, after the substrate treatment process, supplying cleaning plasma including cleaning gas in the processing chamber during a cleaning process; and supplying the inert dilution gas at a second flow rate that is less than the first flow rate to the pumping exhaust system during the cleaning process.

FIELD

The present disclosure relates to substrate processing systems, and moreparticularly to pumping exhaust systems of substrate processing systems.

BACKGROUND

The background description provided here is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this background section, aswell as aspects of the description that may not otherwise qualify asprior art at the time of filing, are neither expressly nor impliedlyadmitted as prior art against the present disclosure.

Substrate processing systems may be used to perform substrate treatmentsuch as deposition or etching of film on a substrate. Substrateprocessing systems typically include a processing chamber with asubstrate support (such as a pedestal, a chuck, a plate, etc.) arrangedtherein. A substrate such as a semiconductor wafer is arranged on thesubstrate support during treatment. A gas diffusion device such as ashowerhead may be arranged in the processing chamber to deliver anddisburse process gases and purge gases as needed.

In some applications, the film is deposited using plasma-enhancedchemical vapor deposition (PECVD) or plasma-enhanced atomic layerdeposition (PEALD). During PEALD, one or more cycles are performed todeposit film on the substrate. Each PEALD cycle typically includesprecursor dose, dose purge, RF plasma dose, and RF purge steps. Duringdeposition, process gas may be delivered to the processing chamber usingthe showerhead. During RF plasma dosing, RF power is supplied to theshowerhead and the substrate support is grounded (or vice versa).

Evacuation of reactants may be performed using reduced pressure pumpingthrough an exhaust connector that is connected to an inlet of adownstream pump. An outlet of the downstream pump is input to anabatement device that typically includes a gas burner and a waterscrubber. An output of the abatement device is usually connected to afacility scrubbed exhaust system.

Some process gas combinations form solid effluent build-up in exhaustlines of the pumping exhaust system. To prevent solid effluent buildup,heated inert dilution gas is injected into the exhaust pumping systemand the pump and/or exhaust lines are heated to prevent condensation.Over time, however, the exhaust lines connecting the processing chamber,the downstream pump and the abatement device become increasingly blockeddue to effluent buildup. As a result, the process may not perform asintended and defects may increase due to the reduced exhaust flow rate.Eventually, the exhaust lines become sufficiently blocked such that theprocessing chamber needs to be taken off line and the exhaust lines needto be replaced or otherwise repaired.

Some process gas combinations such as silicon precursor and oxidizer maybe more reactive at higher temperatures and pressures. Therefore, theapproach of reducing buildup in the exhaust lines by heating up theinert dilution gas, the exhaust lines and the pump to preventcondensation cannot be used due to increased reaction rates.

SUMMARY

A method for reducing effluent buildup in a pumping exhaust system of asubstrate processing system includes, during a substrate treatmentprocess, arranging a substrate on a substrate support in a processingchamber; supplying one or more process gases to the processing chamber;supplying an inert dilution gas at a first flow rate to the pumpingexhaust system; performing substrate treatment on the substrate in theprocessing chamber; evacuating reactants from the processing chamberusing a pumping exhaust system. The method includes, after the substratetreatment process, supplying cleaning plasma including cleaning gas inthe processing chamber during a cleaning process; and supplying theinert dilution gas at a second flow rate that is less than the firstflow rate to the pumping exhaust system during the cleaning process.

In other features, the pumping exhaust system includes a valve, a pump,an abatement device and exhaust lines connecting the valve to theprocessing chamber, the pump to the valve, and the abatement device tothe pump.

In other features, the inert dilution gas is supplied between at leastone of the valve and the pump, and the pump and the abatement device.The substrate treatment process includes one of plasma-enhanced atomiclayer deposition and plasma-enhanced chemical vapor deposition. The oneor more process gases include precursor gas, an oxidizing gas and aninert gas. The precursor gas includes silicon precursor gas. Theoxidizer gas is selected from a group including molecular oxygen andnitrous oxide. The inert dilution gas includes molecular nitrogen.

In other features, the exhaust pumping system includes a pump with aresistive heater. During the clean process, the resistive heater is notactivated.

In other features, the process gas includes a precursor gas and anoxidizer gas. The first flow rate is greater than a first predeterminedflow rate that is sufficient to prevent combustion of the precursor gasand the oxidizer gas in the pumping exhaust system. The second flow rateis at a second predetermined flow rate that would be insufficient toprevent combustion of the precursor gas and the oxidizer gas if usedduring the substrate treatment process. The first flow rate is greaterthan or equal to twice the second flow rate.

In other features, supplying the cleaning plasma includes supplying thecleaning gas to the processing chamber during a cleaning process andstriking the cleaning plasma in the processing chamber.

In other features, supplying the cleaning plasma includes remotelygenerating the cleaning plasma and supplying the cleaning plasma to theprocessing chamber.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example of a substrateprocessing system including a pumping exhaust system according to thepresent disclosure;

FIG. 2 is a functional block diagram of an example of the pumpingexhaust system according to the present disclosure;

FIG. 3 is a flowchart illustrating a method for operating the pumpingexhaust system according to the present disclosure;

FIG. 4 is a flowchart illustrating a method for operating the pumpingexhaust system using a remote plasma source during cleaning according tothe present disclosure.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

The pumping exhaust system and method according to the presentdisclosure is performed after a substrate treatment process. Forexample, the substrate treatment process may include film depositionusing a plasma-enhanced atomic layer deposition (PEALD) process, aplasma-enhanced chemical vapor deposition (PECVD) process, low pressureCVD (LPCVD), furnace ALD, furnace deposition, thermal ALD, or othersubstrate treatment process. While film deposition is described herein,other types of substrate treatment can be performed. The film depositionis performed using process gases. In some examples, the process gasesinclude one or more precursor gases, an oxidizer and a carrier gas,although other process gases can be used.

As described above, over time solid effluent builds up in the pump andthe exhaust lines of the pumping exhaust system. To reduce buildup ofeffluent during film deposition, the inert dilution gas is typicallysupplied to the pumping exhaust system to reduce partial pressures ofthe reactants in the exhaust lines. In some examples, the inert dilutiongas is supplied at a first flow rate that is greater than apredetermined flow rate that is sufficient to prevent combustion in theexhaust lines given the flowrates, the precursor type, and the oxidizertype that are used.

When using deposition process gases including certain precursor andoxidizer gases, a resistive heater of the pump is not used duringdeposition to reduce the likelihood of reaction. In some examples,cooling of the pump is also performed using a pump cooling system.

After substrate treatment, inner surfaces of the processing chamber arecleaned using a cleaning process. The cleaning process uses RF plasmagas including a fluorine-based gas species to remove film buildup on theinner surfaces of the processing chamber. In prior systems, the dilutiongas flow rate is maintained at the same flow rate in the pumping exhaustsystem during both the deposition process and the cleaning process.

According to the present disclosure, a second flow rate of the inertdilution gas that is supplied to the pumping exhaust system is reducedduring the cleaning process below the first flow rate used during thedeposition process. Because the second flow rate is reduced, a residencetime and partial pressure of activated fluorine gas species is increasedin the exhaust lines of the pumping exhaust system. As a result, solideffluent in the exhaust lines is etched during the cleaning process.

More particularly, during substrate treatment, the inert dilution gas isflowed at the first flow rate in order to reduce the partial pressuresof the reactants in the exhaust lines. In some examples, the first flowrate is greater than a predetermined flow rate that is sufficient toprevent combustion in the exhaust lines given the flowrates, theprecursor type and the oxidizer type that are used. In some examples,the inert dilution gas is provided at a flow rate in a range from 100standard liters per minute (slm) to 300 slm. For example, 190 slm may beused.

In some examples, the second flow rate of the inert dilution gas is lessthan the first flow rate. In some examples, the second flow rate usedduring the cleaning process would be insufficient to prevent combustionhad it been used during the substrate treatment process. In someexamples, the second flow rate is in a range 10 to 90 slm during thecleaning process, although other flow rates can be used.

Referring now to FIG. 1, an example of a substrate processing system 10includes a processing chamber 12 with a reaction volume. While aspecific processing chamber example is shown, other types of processesand/or processing chambers may be used. Process gases may be supplied tothe processing chamber 12 using a showerhead 14. In some examples, theshowerhead 14 is a chandelier-type showerhead. A secondary purge gassystem 13 may be used to inject secondary purge gas between an uppersurface of the showerhead 14 and a top surface of the processing chamber12. The secondary purge gas system 13 may include a collar 15 that isarranged around a stem of the showerhead and that includes gas holes(not shown) for injecting secondary purge gas laterally between theshowerhead 14 and a top surface of the processing chamber 12.

A substrate 18 such as a semiconductor wafer may be arranged on asubstrate support 16 during processing. The substrate support 16 mayinclude a pedestal, an electrostatic chuck, a mechanical chuck or othertype of substrate support.

A gas delivery system 20 may include one or more gas sources 22-2, 22-2,. . . , and 22-N (collectively gas sources 22), where N is an integergreater than one. Valves 24-1, 24-2, . . . , and 24-N (collectivelyvalves 24), mass flow controllers 26-1, 26-2, . . . , and 26-N(collectively mass flow controllers 26), or other flow control devicesmay be used to controllably supply one or more gases to a manifold 30,which supplies a gas mixture to the processing chamber 12.

A controller 40 may be used to monitor process parameters such astemperature, pressure etc. (using one or more sensors 41) and to controlprocess timing. The controller 40 may be used to control process devicessuch as the gas delivery system 20, a substrate support heater 42,and/or an RF plasma generator 46. The controller 40 may also be used toevacuate reactants from the processing chamber 12 using a pumpingexhaust system 50.

The RF plasma generator 46 selectively generates the RF plasma in theprocessing chamber. The RF plasma generator 46 may be an inductive orcapacitive-type RF plasma generator. In some examples, the RF plasmagenerator 46 may include an RF supply 60 and a matching and distributionnetwork 64. While the RF plasma generator 46 is shown connected to theshowerhead 14 and the substrate support is grounded or floating, the RFplasma generator 46 can be connected to the substrate support 16 and theshowerhead 14 can be grounded or floating. In some examples, purge gas80 may be selectively supplied to the secondary purge gas system 13 by avalve 82.

During cleaning, a cleaning plasma process gas may be supplied to theprocessing chamber and plasma may be struck in the chamber as describedabove. Alternately, a remote plasma source 90 may be used to supplycleaning plasma to the processing chamber. In some examples, thecleaning plasma process gas or remote cleaning plasma may include afluorine gas species such as nitrogen trifluoride (NF₃),hexafluoroethane (C₂F₆), or other fluorine gas species.

Referring now to FIG. 2, the pumping exhaust system 50 is shown infurther detail. The pumping exhaust system 50 includes a valve 110, apump 114 and an abatement device 118. In some examples, the valve 110includes a throttle valve, although other types of values may be used.An output of the abatement device 118 is in fluid communication with afacility scrubbed exhaust system 122. In some examples, the abatementdevice 118 includes a gas burner for igniting reactants and a scrubbersuch as a water scrubber (both not shown). In some examples, exhaustlines 126 connecting the processing chamber, the valve 110, the pump114, the abatement device 118, and the facility scrubbed exhaust system122 are heated by a heater 128 to prevent condensation in the exhaustlines 126. In some examples, the exhaust lines 126 are heated to atemperature range between 90 and 110° C. In some examples, the heater128 includes a resistive heat wrap arranged around the exhaust lines126.

During deposition and/or cleaning, an inert dilution gas may be injectedinto the exhaust lines between the valve 110 and the pump 114 and/orbetween the pump 114 and the abatement device 118. The locations atwhich the inert gas is injected may depend in part upon the capacity ofthe pump 114. In some examples when the pump 114 can handle the flowrate of gases from the processing chamber 12 and the additional inertdilution gas to be injected, the inert dilution gas is only injectedbetween the valve 110 and the pump 114 and is not injected between thepump 114 and the abatement device 118.

In implementations where the inert dilution gas is injected between thevalve 110 and the pump 114, a mass flow meter 134 and a valve 138 areused to control flow of the inert dilution gas from a gas source 130. Insome examples, a direction that the inert dilution gas is injected is inthe same direction as the flow in the lines 126 between the valve 110and the pump 114 (rather than at a right angle as shown). Inimplementations where the inert gas is injected between the pump 114 andthe abatement device 118, a mass flow meter 142 and a valve 144 are usedto control flow of the inert dilution gas from a gas source 140. In someexamples, a direction that the inert dilution gas is injected is in thesame direction as the flow in the lines 126 between the pump 114 and theabatement device 118, although other directions may be used.

In some examples, the pump 114 includes a resistive heater 150 forheating reactants and inert dilution gas flowing through the pump 114.In some examples, the pump includes a cooling system 152 that suppliescooling fluid 154 to a cooling channel 158 using a pump 156. The coolingsystem 152 may be used to cool reactant gases and inert dilution gasflowing through the pump 114.

Referring now to FIG. 3, a method 200 for removing effluent buildup inthe pumping exhaust system 50 is shown. At 208, a substrate is arrangedin the processing chamber 12 on the substrate support 16. At 210,process parameters including process gas flows are set. For example,precursor gas flow, optional oxidizer gas flow and carrier gas flow areset by the gas delivery system 20 and the controller 40. At 214, aninert dilution gas is supplied to the pumping exhaust system at thefirst flow rate. At 218, RF plasma is struck in the processing chamber.At 222, the substrate is treated. For example, film is deposited on thesubstrate in the processing chamber during a deposition period. At 226,the plasma is extinguished after the deposition period. At 230, reactantgases are evacuated from the chamber. For example, a purge process maybe performed by supplying an inert dilution gas to the processingchamber. At 232, the substrate is removed.

At 234, cleaning gas is supplied to the processing chamber. In someexamples, the cleaning gas includes a fluorine gas species and a carriergas. At 238, a flow rate of the inert dilution gas to the pumpingexhaust system is reduced to the second flow rate that is lower than thefirst flow rate. At 242, RF plasma is struck in the processing chamber.At 246, the RF plasma is extinguished after a predetermined cleaningperiod.

Referring now to FIG. 4, the method of FIG. 3 can be modified using aremote plasma source. After 232, remote plasma including a fluorinespecies is supplied to the processing chamber for a predeterminedcleaning period at 250. Before the cleaning process or while thecleaning process is performed, the flow rate of inert dilution gas tothe exhaust pumping system is reduced to the second flow rate at 252.When the predetermined cleaning period is up, the supply of remoteplasma from the remote plasma source is stopped at 254.

In some examples, the gas delivery system delivers a process gas mixtureincluding a precursor, an oxidizer and one or more carrier gases. Insome examples, the precursor gas includes a silicon precursor gas. Insome examples, the oxidizer gas includes nitrous oxide (N₂O) ormolecular oxygen (O₂) and the carrier gas includes argon (Ar), althoughother oxidizers and carrier gases may be used. In some examples, thecleaning gas may include a fluorine gas species such as nitrogentrifluoride (NF₃), hexafluoroethane (C₂F₆), or other fluorine gasspecies. In some examples, the inert dilution gas supplied to thepumping exhaust system includes molecular nitrogen (N₂), although otherinert dilution gases may be used.

In some examples during wafer processing, the inert dilution gas has aflow rate in a range 100 to 300 standard liters per minute (slm) toreduce the partial pressure of reactants in the exhaust lines. In someexamples, the inert dilution gas has a flow rate in a range from 150 to250 slm during wafer processing. In some examples, the inert dilutiongas has a flow rate in a range 170 to 210 slm during wafer processing.In some examples, the inert dilution gas has a flow rate of 190 slmduring wafer processing.

In some examples, the inert dilution gas has a flow rate in a range 10to 90 standard liters per minute (slm) to increase a residence time ofthe fluorine gas in the lines 126 of the pumping exhaust system 50during RF plasma cleaning. In some examples, the inert dilution gas hasa flow rate in a range 30 to 70 slm during RF plasma cleaning. In someexamples, the inert dilution gas has a flow rate in a range 10 to 30 slmduring RF plasma cleaning. In some examples, the inert dilution gas hasa flow rate in a range from 60 to 70 slm during RF plasma cleaning. Insome examples, the first flow rate is greater than or equal to twice thesecond flow rate. In some examples, the first flow rate is greater thanor equal to three times the second flow rate.

In some examples, the systems and methods according to the presentdisclosure also reduce pump and inert dilution gas temperatures duringRF plasma cleaning of the processing chamber to reduce the reactionrate. This serves to increase partial pressure and residence time of thecleaning gas and reactive fluorine components in the pumping exhaustsystem. In some examples, the inert dilution gas is heated duringcompression by the pump. In some examples, additional heat is suppliedby the resistive heater 150 during deposition. In some examples, theresistive heater 150 is turned off during the cleaning process and/orthe cooling system 152 is used to further cool the inert dilution gasduring RF plasma clean.

In some examples, the controller 40 initiates the decrease in the flowrate of the inert dilution gas when the cleaning gas is supplied. Forexample, when the cleaning gas (such as NF₃) is supplied, the signal canbe used to switch the inert dilution gas from the first or higher flowrate for deposition (such as 150 slm, 190 slm, or 210 slm) to the secondor lower flow rate for cleaning (such as 10 slm, 20 slm, 65 slm, etc.).

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In some implementations, a controller is part of a system, which may bepart of the above-described examples. Such systems can comprisesemiconductor processing equipment, including a processing tool ortools, chamber or chambers, a platform or platforms for processing,and/or specific processing components (a wafer pedestal, a gas flowsystem, etc.). These systems may be integrated with electronics forcontrolling their operation before, during, and after processing of asemiconductor wafer or substrate. The electronics may be referred to asthe “controller,” which may control various components or subparts ofthe system or systems. The controller, depending on the processingrequirements and/or the type of system, may be programmed to control anyof the processes disclosed herein, including the delivery of processinggases, temperature settings (e.g., heating and/or cooling), pressuresettings, vacuum settings, power settings, radio frequency (RF)generator settings, RF matching circuit settings, frequency settings,flow rate settings, fluid delivery settings, positional and operationsettings, wafer transfers into and out of a tool and other transfertools and/or load locks connected to or interfaced with a specificsystem.

Broadly speaking, the controller may be defined as electronics havingvarious integrated circuits, logic, memory, and/or software that receiveinstructions, issue instructions, control operation, enable cleaningoperations, enable endpoint measurements, and the like. The integratedcircuits may include chips in the form of firmware that store programinstructions, digital signal processors (DSPs), chips defined asapplication specific integrated circuits (ASICs), and/or one or moremicroprocessors, or microcontrollers that execute program instructions(e.g., software). Program instructions may be instructions communicatedto the controller in the form of various individual settings (or programfiles), defining operational parameters for carrying out a particularprocess on or for a semiconductor wafer or to a system. The operationalparameters may, in some embodiments, be part of a recipe defined byprocess engineers to accomplish one or more processing steps during thefabrication of one or more layers, materials, metals, oxides, silicon,silicon dioxide, surfaces, circuits, and/or dies of a wafer.

The controller, in some implementations, may be a part of or coupled toa computer that is integrated with the system, coupled to the system,otherwise networked to the system, or a combination thereof. Forexample, the controller may be in the “cloud” or all or a part of a fabhost computer system, which can allow for remote access of the waferprocessing. The computer may enable remote access to the system tomonitor current progress of fabrication operations, examine a history ofpast fabrication operations, examine trends or performance metrics froma plurality of fabrication operations, to change parameters of currentprocessing, to set processing steps to follow a current processing, orto start a new process. In some examples, a remote computer (e.g. aserver) can provide process recipes to a system over a network, whichmay include a local network or the Internet. The remote computer mayinclude a user interface that enables entry or programming of parametersand/or settings, which are then communicated to the system from theremote computer. In some examples, the controller receives instructionsin the form of data, which specify parameters for each of the processingsteps to be performed during one or more operations. It should beunderstood that the parameters may be specific to the type of process tobe performed and the type of tool that the controller is configured tointerface with or control. Thus as described above, the controller maybe distributed, such as by comprising one or more discrete controllersthat are networked together and working towards a common purpose, suchas the processes and controls described herein. An example of adistributed controller for such purposes would be one or more integratedcircuits on a chamber in communication with one or more integratedcircuits located remotely (such as at the platform level or as part of aremote computer) that combine to control a process on the chamber.

Without limitation, example systems may include a plasma etch chamber ormodule, a deposition chamber or module, a spin-rinse chamber or module,a metal plating chamber or module, a clean chamber or module, a beveledge etch chamber or module, a physical vapor deposition (PVD) chamberor module, a chemical vapor deposition (CVD) chamber or module, anatomic layer deposition (ALD) chamber or module, an atomic layer etch(ALE) chamber or module, an ion implantation chamber or module, a trackchamber or module, and any other semiconductor processing systems thatmay be associated or used in the fabrication and/or manufacturing ofsemiconductor wafers.

As noted above, depending on the process step or steps to be performedby the tool, the controller might communicate with one or more of othertool circuits or modules, other tool components, cluster tools, othertool interfaces, adjacent tools, neighboring tools, tools locatedthroughout a factory, a main computer, another controller, or tools usedin material transport that bring containers of wafers to and from toollocations and/or load ports in a semiconductor manufacturing factory.

1. A method for reducing effluent buildup in a pumping exhaust system ofa substrate processing system, comprising: during a substrate treatmentprocess: arranging a substrate on a substrate support in a processingchamber; supplying one or more process gases to the processing chamber;supplying an inert dilution gas at a first flow rate to the pumpingexhaust system; performing substrate treatment on the substrate in theprocessing chamber; and evacuating reactants from the processing chamberusing a pumping exhaust system; and after the substrate treatmentprocess: supplying cleaning plasma including cleaning gas in theprocessing chamber during a cleaning process; and supplying the inertdilution gas at a second flow rate that is less than the first flow rateto the pumping exhaust system during the cleaning process.
 2. The methodof claim 1, wherein the pumping exhaust system includes a valve, a pump,an abatement device and exhaust lines connecting the valve to theprocessing chamber, the pump to the valve, and the abatement device tothe pump.
 3. The method of claim 2, wherein the inert dilution gas issupplied between at least one of: the valve and the pump; and the pumpand the abatement device.
 4. The method of claim 2, wherein thesubstrate treatment process includes one of plasma-enhanced atomic layerdeposition and plasma-enhanced chemical vapor deposition.
 5. The methodof claim 1, wherein the one or more process gases include precursor gas,an oxidizing gas and an inert gas.
 6. The method of claim 5, wherein theprecursor gas includes silicon precursor gas.
 7. The method of claim 5,wherein the oxidizer gas is selected from a group including molecularoxygen and nitrous oxide.
 8. The method of claim 1, wherein the inertdilution gas includes molecular nitrogen.
 9. The method of claim 1,wherein: the exhaust pumping system includes a pump with a resistiveheater; and during the clean process, the resistive heater is notactivated.
 10. The method of claim 1, wherein: the process gas includesa precursor gas and an oxidizer gas; the first flow rate is greater thana first predetermined flow rate that is sufficient to prevent combustionof the precursor gas and the oxidizer gas in the pumping exhaust system;and the second flow rate is at a second predetermined flow rate thatwould be insufficient to prevent combustion of the precursor gas and theoxidizer gas if used during the substrate treatment process.
 11. Themethod of claim 1, wherein the first flow rate is greater than or equalto twice the second flow rate.
 12. The method of claim 1, whereinsupplying the cleaning plasma includes: supplying the cleaning gas tothe processing chamber during a cleaning process; and striking thecleaning plasma in the processing chamber.
 13. The method of claim 1,wherein supplying the cleaning plasma includes: remotely generating thecleaning plasma; and supplying the cleaning plasma to the processingchamber.